[time-nuts] Making a HP 10811 better

Ed Palmer ed_palmer at sasktel.net
Sun Mar 28 20:20:46 UTC 2010 

Have you considered putting the 10811 in a deep freeze? :-)

The March 1981 issue of the HP Journal includes an in-depth article on 
the 10811A/B.  It talks about the heater, thermal gain, optimization, 
etc.  Figure 5 on page 21 shows a graph of ambient temperature vs. 
frequency change.  The figure shows that the lowest frequency changes 
occur around an ambient temperature of -20C!  Maybe instead of an outer 
oven we need to use a Peltier cooler.

http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1981-03.pdf

Ed

WarrenS wrote:
>
> Richard wrote approx
>> ... This is how the Thermal gain can be increase to eliminate 
>> temperature drift over typical room variations.
>
> Thank You
> Great Idea. Wish I would of thought of that. But Yeah almost as good, 
> Now I know it, can take that away.
> That is the type of useful and not obvious information that I was 
> hoping for.
>
> THANKS SO MUCH
> That goes to the top of my list to find a procedure to do it.
> You are a true Nut hero.
>
> WS
>
> ********************
>
> ----- Original Message ----- From: "Richard H McCorkle" 
> <mccorkle at ptialaska.net>
> To: "Discussion of precise time and frequency measurement" 
> <time-nuts at febo.com>
> Sent: Sunday, March 28, 2010 11:32 AM
> Subject: Re: [time-nuts] Making a HP 10811 better
>
>
>> Warren,
>> One thing Rick Karlquist pointed out is a higher thermal gain can be
>> realized to minimize temperature effects by optimizing the heater
>> transistor balance. The 10811A/B Quartz Crystal Oscillator Operating
>> & Service Manual describes the balance circuit in section 8-40. The
>> two heater transistors are not equally spaced with Q7 being closer
>> to the crystal so rather than 50% of the current flowing thru both
>> heater transistors the current in Q8 is set slightly higher at 57%
>> +/- 2% in a production unit to apply equal heat at the crystal.
>>  The typical thermal gain on a production unit is on the order of
>> 100 without optimization, but gains of 1000 or more are possible if
>> the heater transistor balance is optimized. I was fortunate enough
>> to obtain a set of single oven 10811-60158 units that had been
>> optimized by an HP engineer for different temperature sensitivities
>> and tagged as such. The unit optimized for maximum thermal gain is
>> virtually immune to typical room temperature variations. A second
>> unit optimized for double oven operation has much lower thermal
>> gain and makes a great unit for testing software temperature
>> compensation routines and outer oven designs.
>>
>> Richard
>>
>>>
>>> Time to Push the "reset button"
>>>
>>> I hope we can all agree what one is not going to find an axes that 
>>> makes the
>>> Frequency modulation that is caused by tapping on the Oscillator, or 
>>> the
>>> table or the airplane, or the boat, to go away, for whatever reasons.
>>>
>>> Sorry, what I've been falsely referring to as the zero-G axes is 
>>> actually
>>> the "Zero Tilt" angle axes.
>>> I have not had problems with My G changing short term, (BUT it would be
>>> interesting to see if I can detect the moon overhead).
>>> What I do have is some problems with the Osc tilt angle changing due 
>>> to its
>>> position changing a little.
>>> It is the Zero-tilt angle axes that works over a very small change 
>>> of a few
>>> degrees at most.
>>>
>>> On the other hand, the Zero tilt axes is in fact the Max G 
>>> sensitivity axes.
>>> If you want the Min G sensitivity axes, so that there is no change when
>>> turning the Osc over, That is 90 deg from the zero tilt axes, which 
>>> is also
>>> how you make the Osc into its best Tilt angle meter.
>>> What happens at any G value that is between +1 and -1, or is greater 
>>> than +1
>>> or -1,  I have not tested for, so I'm not qualified to speculate.
>>> I am only stating that there is an axes where the Oscillator 
>>> frequency is
>>> exactly the same when you turn it exactly over.
>>> AND this is NOT the axes you want to have, If it is going to be 
>>> tilted even
>>> a sub sub fraction of a deg.
>>>
>>> Now can we get back to making the 10811 Osc better?
>>>
>>> ws
>>>
>>> **********************
>>> *************************
>>> From: "Bob Camp" <lists at rtty.us>
>>> Hi
>>>
>>> If your zero g axis only works over a 1/100 G range, you are looking at
>>> something other than acceleration. If you have found an axis with a 
>>> zero, it
>>> should be a just as much a null at 1 mG as at 1 G as at 10 G's. It's 
>>> also
>>> possible that your "zero" is actually a minimum below your test 
>>> resolution
>>> and higher G's bring it up to the point you can measure it. There's no
>>> guarantee of a zero being there.
>>>
>>> Hitting the oscillator makes it vibrate in all three axis, that's 
>>> not going
>>> to be suppressed regardless of which way you have it mounted.
>>>
>>> Bob
>>> *********************
>>> On Mar 28, 2010, at 12:42 AM, WarrenS wrote:
>>>>
>>>> Humm,
>>>> Have to admit, I did not consider that as a possibility before.
>>>> Maybe when I tap on it, its not microphonics after all that cause 
>>>> the freq
>>>> to modulate, but the vibration of the inside stuff that is warming 
>>>> it up.
>>>> For every action there is a reaction and for every  nut there is a
>>>> wing-it-nut.
>>>>
>>>> ws
>>>> *****************
>>>> Hi
>>>>
>>>> If that's the result you are getting, you are measuring something 
>>>> other
>>>> than G sensitivity. Temperature effects possibly.
>>>>
>>>> Bob
>>>>
>>>> ****************
>>>> On Mar 27, 2010, at 11:02 PM, WarrenS wrote:
>>>>
>>>>>
>>>>> Just a friendly comment about the Zero G turn over point and 
>>>>> Vibration
>>>>>
>>>>> Like Zero temp turn over, Special orientation of the OSC ONLY 
>>>>> works good
>>>>> over a VERY SMALL range, (maybe a 1/100 of G change)
>>>>> It would not help vibration and has no effect on microphonics 
>>>>> which are
>>>>> likely a bigger problem anyway.
>>>>> Try taping you Osc, It's freq will go crazy if monitoring it at high
>>>>> resolutions and bandwidths
>>>>>
>>>>> ws
>>>>>
>>>>> ************************
>>>>>
>>>>> Hi
>>>>>
>>>>> The concrete basement floor is your friend.
>>>>>
>>>>> Stay as far away from the blower on the furnace as you can. If you 
>>>>> have a
>>>>> drop forge in the basement avoid it as well :)....
>>>>>
>>>>> You will indeed have a seismograph, but not a very useful one. 
>>>>> There's
>>>>> not a lot of G's at seismic frequencies unless you live in an active
>>>>> earthquake region. The fundamentals of G's and displacement vs 
>>>>> frequency
>>>>> are in your favor in that respect.
>>>>>
>>>>> Bob
>>>>>
>>>>>
>>>>> On Mar 27, 2010, at 12:42 PM, Stanley Reynolds wrote:
>>>>>
>>>>>> Is the source of the vibration important ? I'm thinking that any
>>>>>> vibration that is not on the same axis as gravity. Walking across 
>>>>>> the
>>>>>> lab vs a fan that is out of balance close by. Would a suspended mass
>>>>>> mounting help with vibration isolation and damping with rubber 
>>>>>> pads and
>>>>>> springs or would that just make a seismograph ?
>>>>>>
>>>>>> Stanley
>>>>>>
>>>>>>
>>>>>> ----- Original Message ----
>>>>>> From: Peter Vince <pvince at theiet.org>
>>>>>> To: Discussion of precise time and frequency measurement 
>>>>>> <time-nuts at
>>>>>> febo.com>
>>>>>> Sent: Sat, March 27, 2010 10:51:07 AM
>>>>>> Subject: Re: [time-nuts] Making a HP 10811 better
>>>>>>
>>>>>> Warren,
>>>>>>
>>>>>>   If you turn over an oscillator, is the frequency change
>>>>>> completely reversible (to your "under 1e-12 resolution") when it is
>>>>>> restored?  Thinking aloud, if an hour-glass is turned over twice, 
>>>>>> the
>>>>>> final level will be the same, but the grains will be mixed.  A 
>>>>>> quartz
>>>>>> crystal, however, is solid, so hopefully nothing actually moves.
>>>>>> Presumably the zero-G axis is with the axis of oscillation at 90
>>>>>> degrees to gravity?
>>>>>>
>>>>>>   Peter (the "other" one :-)
>>>>>>
>>>>>>
>>>>>>
>>>>>>> Another thing I use it for is to test high resolution Freq meters.
>>>>>>> Using a calibrated wedge that I can then slide under one edge of 
>>>>>>> the
>>>>>>> zero-G
>>>>>>> Osc box, I can
>>>>>>> make small, variable, repeatable, freq changes of under 1e-12
>>>>>>> resolution,
>>>>>>> something pretty hard to do otherwise.
>>>>>>> If I want to make BIG changes like 1e-10, I can rotate the box 
>>>>>>> on any
>>>>>>> of its
>>>>>>> sides and still use the wedge,
>>>>>>> and for a quick check of new equipment, I just turn the box over 
>>>>>>> which
>>>>>>> then
>>>>>>> gives a couple of parts in 1e-9 freq change.
>>>>>>> It makes a weird but simple and indispensable variable freq 
>>>>>>> source that
>>>>>>> is
>>>>>>> useful for many things, such as checking the LOOP TC of a TBolt.
>>>>
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at febo.com
>>>> To unsubscribe, go to
>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>>>
>>>
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>
>>
>>
>>
>>
>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>

More information about the time-nuts mailing list